1. Field of the Invention
The present invention relates to a pipe connecting structure for a pipe-type modular wiper apparatus for use in a vehicle such as an automobile, a bus, a truck or the like.
2. Description of the Related Art
There has been available a modular wiper apparatus structured in such a manner that a bracket to which the wiper motor is fastened and another bracket to which the wiper shaft is fastened are connected to each other by a pipe member. In a modular wiper apparatus of the type described above, the pipe member and the bracket are connected to each other in such a manner that a cylindrical projection to be inserted into the inner surface of the pipe member is formed on the bracket and the cylindrical projection is inserted into the pipe member at the end portion of the pipe member before a rivet is inserted into a hole formed at a position which corresponds to the projection and the pipe member so as to be riveted. However, the structure of this type necessarily encounters a problem of generation of a gap which will be formed between the inner surface of the pipe member and the projection of the bracket and that between the rivet, the pipe member and the hole formed in the bracket. Therefore, the wiper apparatus suffers from an undesirable play, causing a problem to take place in that, for example, the range which is wiped by the wiper blade is undesirably changed and/or noise is generated.
A pipe nut is sometimes employed for the purpose of fixing another member to the pipe member. The pipe nut in this case is employed as shown in FIG. 4 in such a manner that: a head portion 15a having the lower surface curved along the outer surfaces of the pipe member and the upper surface formed into a flat shape is formed on the top outer surface portion of a cylindrical member; and a female thread 15c is formed in the lower inner surface of the above-described cylindrical member. In this case, the pipe nut 15 is first inserted into a hole formed on the pipe member 6, and then a tool (omitted from illustration) is used in such a manner that a male thread formed on the tool is engaged with the female thread 15c of the pipe nut 15 so as to tighten them, after this process, the tool is pulled together with the female thread 15c. As a result, the intermediate portion of the pipe nut 15 is deformed into a flange shape so that the pipe nut 15 is fixedly secured to a portion within the hole formed in the pipe member 6 while preventing generation of undesirable play around the hole formed in the pipe member.
It might therefore be feasible to employ a structure using the above-described pipe nut 15 as shown in FIG. 5 in such a manner that the bracket 16 is positioned to contact with the flat surface of the head portion 15a of the pipe nut 15 fastened to the pipe member 6 before a bolt 13 is screwed so that the pipe member 6 and the bracket 16 are connected to each other. The above-described structure encounters no problem when load is applied in the axial direction of the bolt because the load can be received by the bolt. However, strength exhibited is unsatisfactory when a load is applied from a direction deviated from the axial direction of the bolt. Therefore, undesirable play takes place, requiring that the strength be further improved.